Reduce size of 'change email' field

* Limit width to match password fields
* Bootstrap 3 fields default to 100% width
Tidy up 'request password reset' form

* Add a breadcrumb to easily navigate back to sign in page
* Add bootstrap form classes, and wrap in grid classes to restrict width
* Remove link at bottom of the page, now available in breadcrumb
Tidy up 'password reset error' page

* Put error message in a bootstrap warning
* Make ‘try again’ action clearer by styling as a button
Tidy up change/choose new password pages

* Add breadcrumbs
* Add vertical space to submit button